Mayors of major cities imposed curfews and governors mobilized state National Guard in an effort to keep the peace overnight but tensions boiled over.

Some major retailers closed hundreds of stores as protests against police violence rolled on this weekend.

In a memo to employees on Sunday, Apple CEO Cook wrote "George Floyd's death is shocking and tragic proof that we must aim far higher than a 'normal' future, and build one that lives up to the highest ideals of equality and justice."

U.S. stock futures fell on Sunday night as Wall Street was set to kick off June trading on a sour note after consecutive monthly gains.

It comes as Trump continues to spar with social media companies over their content policies.